The present invention generally relates to magnetic recording and reproducing systems, and more particularly to a magnetic recording and reproducing system which records and reproduces a video signal and a digital audio signal on and from oblique tracks of a magnetic tape.
Conventionally, there are systems for recording and reproducing a frequency modulated (FM) audio signal on and from a deep layer portion of a magnetic layer on a magnetic tape by use of rotary audio heads and recording and reproducing a video signal on and from a surface layer portion of the magnetic layer on the magnetic tape by use of rotary video heads. According to such systems, the phase of a reproduced FM audio signal obtained from one rotary audio head does not coincide perfectly with the phase of a reproduced FM audio signal obtained from the other rotary audio head at a joint where the switching of the rotary audio heads takes place, due to a difference in the tension of the magnetic tape and the like. As a result, a pulse noise is generated in an audio signal which is obtained by demodulating the reproduced FM audio signal. In addition, since the FM audio signal is an analog signal, the quality of the audio signal becomes deteriorated every time a dub-recording is carried out on the FM audio signal.
For these reasons, in the so-called 8-mm video tape recorders or cameras, a digital audio signal is recorded in a portion of a track which is recorded by the rotary video head. The digital audio signal is subjected to a time base compression before the recording so that it is possible to avoid recording and reproduction at the joint where the switching of the heads takes place, and it is thus possible to prevent the generation of the pulse noise. Furthermore, the deterioration in the quality of the audio signal introduced by the dub-recording is extremely small because the audio signal is recorded and reproduced in the form of a digital signal.
In the 8-mm video tape recorder, error check and correction codes are produced from the digitized audio signal for every one field of the video signal, and a digital audio signal is obtained by an interleaving. Accordingly, the codes are completed within one track. When an assembly editing is carried out to record a new digital audio signal from an arbitrary track of a pre-recorded magnetic tape, it is possible to completely reproduce the previously recorded digital audio signal and the newly recorded digital audio signal even at a joint on the magnetic tape where the assembly editing was started. However, when both the previously recorded digital audio signal and the newly recorded digital audio signal are reproduced and converted into analog audio signals, there is a problem in that a large click noise is generated at the joint of the reproduced analog audio signals.